The objective of this project is to investigate matrix-cell interactions in bone. We employ an experimental model of matrix-induced cartilage and bone differentiation and mineralization. Projects currently under investigation are: 1) the mechanism of action of matrix components in bone induction; 2) influence of local insulin on bone formation; 3) influence of diabetes on fibronectin and matrix-cell interactions; 4) role of vitamin D metabolites in bone formation; 5) experimental rickets and bone marrow function; 6) effect of vitamin A on bone differentiation; and 7) proteoglycans and mineralization of bone.